How Lab-grown sperm makes healthy offspring

SPERM HAVE been
made in the laboratory and
used to father healthy baby
mice in a pioneering move
that could lead to infertility
treatments.
The Chinese research
took a stem cell, converted
it into primitive sperm and
fertilised an egg to produce
healthy pups.
The study, in the Journal
Cell Stem Cell, showed
they were all healthy and
grew up to have offspring
of their own.
Experts said it was a step
towards human therapies.
It could ultimately
help boys whose fertility
is damaged by cancer
treatment, infections such
as mumps or those with
defects that leave them
unable to produce sperm.
Sperm factory
Making sperm in the
testes is one of the longest
and most complicated
processes in the body –
taking more than a month
from start to finish in most
mammals.
Now scientists have been
able to reproduce the feat
in the lab.
An embryonic stem cell,
which can morph into any
other type of tissue, was
guided towards becoming
sperm with a cocktail of
chemicals, hormones and
testicular tissue.
In order to develop
properly, the cell must
go through a crucial and
delicate rearrangement of
its DNA – its code of life –
called meiosis.
Just like a female’s egg,
sperm must lose half
of their chromosomes
(bundles of DNA) so that a
fertilised egg has a normal
amount.
The Chinese research
team says they have met
the international goldstandard
set out for
reproducing meiosis in the
lab.
But they did not create
sperm as you would
recognise them with a head
and a tail for swimming –
they were a stage earlier
known as spermatids.
However, the spermatids
have the correct amount
of genetic information and
were successfully inserted
into mouse eggs through
IVF.
“All the offspring were
healthy and fertile,”
Professor Xiao-Yang Zhao,
from the Chinese Academy
of Sciences, said.
He hopes the study
would offer “inspiration”
for similar work with
human tissue to “solve the
problem of sterility”.
However, he said there
were “ethical concerns”
and “possible risks should
be ruled out first”.
His colleague, Professor
Jiahao Sha, from Nanjing
Medical University, said:
“We think that it holds
tremendous promise for
treating male infertility.”
Spermatids have been
used to create healthy
human babies in Japan. But
the procedure is illegal in
some countries.
Another challenge the
field needs to overcome is
the starting material – no
adult has embryonic stem
cells.
The Chinese group
believes converting skin
cells into a stem-cell state,
which can be done reliably,
will be the solution.
Exciting
Professor Robin Lovell-
Badge, from the UK’s
Francis Crick Institute,
praised “an impressive
amount of work” and
“exciting” results which
will be “fantastically useful
for basic research”.
He said: “I expect many
think it is easy to make
sperm, most men just sit
there and make millions
of the little blighters every
hour. However, as this
paper clearly shows, it is
much more complex than
this.”
While Professor Allan
Pacey, from the University
of Sheffield, argued making
sperm outside the body
“would be a remarkable
thing to be able to do, both
for the advancement of
science and also to be able
to help infertile men”.
He added: “In spite of
these encouraging results,
we are still some way from
immediately applying this
technique as a potential
cure for human male
infertility.”
Culled from bbcnews.com